Laennec's stethoscope

Physicians in early 19th-century Paris examined the chest by tapping it or by laying an ear directly on the patient. René Laennec had learned percussion from his teacher Jean-Nicolas Corvisart, who took it from a book by the Viennese physician Leopold Auenbrugger. Laennec had a gift for pathological anatomy, but his conservative politics long kept him from a senior post, and only after the monarchy returned in 1815 was he given a position at the Necker Hospital.

In his own account, Laennec was consulted in 1816 about a young woman with signs of heart disease. She was stout, so feeling and tapping the chest told him little, and her age and sex ruled out putting his ear to her chest. He recalled that a pin scratched at one end of a wooden beam is heard clearly at the other. He rolled a quire of paper into a tight cylinder, placed one end over her heart, and heard the heartbeat more distinctly than he ever had with his bare ear.

He began a series of observations at the Necker at once and had not interrupted them when he wrote his book. Glass and metal carried the sounds less well than lighter materials and felt cold in winter, so he settled on a wooden cylinder with a narrow bore, made in two halves joined by a screw so it could be carried. A funnel-shaped end served for breathing and the crackles he called râles; a wooden plug turned it into a plain tube for the voice and the heart. He named it the stethoscope, from the Greek words for chest and for looking.

De l'auscultation médiate appeared in Paris in two volumes in 1819. Laennec wrote that the new signs made the diagnosis of almost all diseases of the lungs, pleura and heart more certain, and he set them out in turn: the voice heard through the cylinder, the breath sounds, and the râles.

His stethoscope had one earpiece. After rubber came into use it gave way to instruments with pieces that fit into both ears, the form most doctors carry now.